For decades, the giant ancient shark Otodus megalodon has loomed in our imaginations as a horror of the ancient seas — an enormous, meat-seeking missile evolved to annihilate whales and nothing less. Scientists pictured it cruising the Miocene oceans with a singular purpose: to shred, swallow, and dominate. It was, we thought, the apex of apex predators.
In reality, the fearsome 80-foot-long megalodon was. Likely not a picky eater. New research suggests that this prehistoric giant shark was less of a specialized leviathan and more of a marine opportunist — gorging on whatever prey the seas served up, whether that meant whales, fish, or smaller sharks.
It may have been the king of the food chain, but it was the kind of adaptable monarch that knew how to scavenge as well as slay.
“They must have fed throughout the food web, on many different species,” said Jeremy McCormack, a geoscientist at Goethe University Frankfurt and the lead author for this new study that challenges the old stereotype of megalodon as a singular whale-slayer.
“It was flexible enough to feed on smaller animals to fulfill its dietary requirements.”
Flexibility, not ferocity alone, may have helped megalodon thrive for nearly 20 million years — and that same flexibility may now explain how it eventually vanished.
Tracking a Shark Through the Food Web
The megalodon, which lived from about 20 to 3.6 million years ago, was the largest predatory fish in Earth’s history. Its serrated teeth — some up to 7 inches long — are among the most iconic fossils ever discovered. But as formidable as those teeth appear, their chemical makeup is even more revealing.
In the new study, McCormack and his international team analyzed the zinc isotope ratios in 209 fossilized teeth from 19 marine species — including Otodus megalodon and its close relatives — found in two key early Miocene sites in southern Germany: Sigmaringen and Passau. The isotopes of zinc preserved in dental enamel can serve as geochemical breadcrumbs, marking an animal’s position in the food web.
The results were striking. Rather than occupying a fixed position at the very top of the marine pyramid, megalodon appears to have sampled broadly across the food web.
“They were not concentrating on certain prey types, but they must have fed throughout the food web, on many different species,” McCormack told CNN.
The findings challenge long-standing assumptions that megalodon fed almost exclusively on whales and other large marine mammals. Bite marks on fossil whale bones have supported that view, but those traces tell only part of the story.
“Of course, you can see bite marks on the bones of marine mammals,” McCormack said. “But you will not see them if they fed on other sharks, because sharks don’t have bones.”
Not the Sole King of the Seas
Another revelation: megalodon wasn’t alone at the top. The zinc data indicate that it shared the apex predator role with other massive sharks like Otodus chubutensis and Araloselachus cuspidatus.
“While certainly this was a fierce apex predator, and no one else would probably prey on an adult megalodon, it’s clear that they themselves could potentially feed on almost everything else that swam around,” McCormack explained.
That ecological flexibility mirrors the feeding habits of the modern great white shark (Carcharodon carcharias), which also shifts from fish to marine mammals as it matures.
And that parallel may not be coincidental.
“Our new study, that demonstrates the ‘diet overlap’ between the great white shark and megalodon, strengthens the idea that the evolution of the smaller, likely more agile and maneuverable great white shark could have indeed driven megalodon to extinction,” said coauthor Kenshu Shimada, a paleobiologist at DePaul University.
Despite its size and bite force, megalodon may have lost out to its smaller rival in a battle of ecological efficiency.
The Bigger Picture: Lessons from Zinc
The study adds to a growing body of research that uses geochemical proxies to peer into ancient ecosystems. Zinc isotope analysis is a relatively new tool in paleontology, but its power is becoming clear.
By measuring how much of the heavy isotope zinc-66 remains in fossilized teeth, scientists can reconstruct ancient food webs with unprecedented resolution. The further up the food chain an animal feeds, the lower its zinc-66 levels — a pattern driven by how zinc is processed in the body.
Using this method, McCormack’s team was able to identify at least three distinct trophic levels among Miocene marine vertebrates. Sea bream occupied the base, followed by small sharks and dolphins, with large sharks like megalodon near the top — but not always at the pinnacle.
“It gives us important insights into how the marine communities have changed over geologic time,” said Shimada, “but more importantly the fact that even ‘supercarnivores’ are not immune to extinction.”
What We Still Don’t Know
Despite this wealth of new data, many mysteries about megalodon remain. No complete skeleton has ever been found. Its physiology, behavior, and even true size are still debated. Some models suggest it grew as long as 52 feet, while others argue it may have reached 80 feet — larger than the fictional monster in The Meg.
And while this study sheds light on what megalodon ate, it doesn’t resolve how its flexible diet evolved or how it may have varied across the globe.
Still, the zinc trail offers a compelling narrative: megalodon wasn’t a mindless whale-killing machine. It was a highly adaptable predator, a marine opportunist.
As McCormack put it, “Determining tooth zinc isotope ratios has once again proven to be a valuable instrument for paleoecological reconstructions.”
In the end, the ocean’s fiercest predator may have survived by being less fearsome and more flexible — until, of course, it didn’t survive at all.
The findings appeared in the journal Earth and Planetary Science Letters.
